1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a semiconductor device suitable as a driver LSI for a liquid crystal display (LCD).
2. Description of the Related Art
Conventionally, in order to reduce electronic modules or devices in size and cost and simplify their configurations, there is a known TCP (tape carrier package) which has a carrier tape having a device hole and wiring such as inner leads, a semiconductor element (e.g., a semiconductor chip) mounted on and electrically connected to the carrier tape, and the resin-encapsulating layer to seal the connecting portion.
Especially, for the LCD which is a thin and low-power consuming display, TCP which has a quite slim semiconductor chip mounted on a tape having a device hole smaller than the chip, and is configured to be connectable in two directions on the long sides of the semiconductor chip, is used as a driver LSI. Such TCP, which is an ultra narrow TCP, will be called UNT hereinafter.
FIG. 8A and FIG. 8B show the structure of the UNT. In the drawings, reference numeral 1 shows a film carrier tape made of polyimide resin or the like. This tape has long and narrow rectangular device holes 2. The device holes 2 are formed to have long sides and short sides, which are smaller than those of the semiconductor chip to be described afterward. The short sides are arranged in parallel with the longitudinal direction (indicated by the arrow) of the carrier tape 1. One face of the carrier tape 1 has wiring such as a group of inner leads (not shown). Each inner lead has its leading ends protruded from two long sides of the device hole 2.
Reference numeral 3 shows the semiconductor chip mounted in a device hole region of the carrier tape 1. The semiconductor chip 3 is electrically connected to the inner leads through bumps of Au or the like. Furthermore, a resin-encapsulating layer 4 of epoxy resin or the like is externally formed on the surface of the semiconductor chip 3 where electrode pads are formed and the connections of the semiconductor chip 3 and the inner leads. The resin-encapsulating layer 4 is formed by a method for dispensing to apply a liquid encapsulating resin by a dispenser for example. Reference numeral 5 shows a dummy inner lead (hereinafter called the dummy lead) with its leading ends protruded from the short sides of the device holes 2. The dummy lead 5 is connected to the electrode pad of the semiconductor chip 3 so to serve to mechanically support and fix the semiconductor chip 3.
The conventional UNT configured as described above, however, has the device hole 2 with its long and short sides made shorter than the corresponding sides of the semiconductor chip 3, allowing substantially no gap between the semiconductor chip 3 and the inner peripheral surface of the device hole 2. Accordingly, the encapsulating resin dispensed onto the electrode pad-formed surface of the semiconductor chip 3, flows to the lower face (opposite from the wiring-formed face) of the carrier tape 1 in such a small amount (expanding length) of about 200 .mu.m from the end faces of the semiconductor chip 3 on the long and short sides. Therefore, a strength of adhesive of the resin-encapsulating layer 4 on the short sides of the semiconductor chip 3 is insufficient.
Specifically, such a semiconductor device has the carrier tape 1 die-cut on the side slightly outside of the resin-encapsulating layer 4, bent or folded into an appropriate shape and mounted on a mother board. Therefore, the resin-encapsulating layer 4 is required to have a strength of adhesive of at least 10 N (Newton) per unit area (m.sup.2) against the carrier tape 1.
But, in the conventional UNT, the resin-encapsulating layer 4 formed on the short sides of the semiconductor chip 3 has such a low strength of adhesive of 2 N/m.sup.2 that the resin-encapsulating layer 4 is cracked in the steps of die-cutting and folding of the carrier tape 1. As a result, the inner leads and the semiconductor chip 3 may have a defective connection or a breakage in the inner leads.